Lars Palapies

Transcoronary gradients of vascular miRNAs and coronary atherosclerotic plaque characteristics

AIMS Circulating microRNAs (miRs) may reflect pathophysiologically relevant processes in the atherosclerotically diseased coronary arterial wall. Given the unmet medical need to identify patients with an unstable plaque phenotype, we determined the relation of circulating atherosclerosis-regulatory miRs with plaque phenotypes. METHODS AND RESULTS We assessed coronary atherosclerotic plaque burden and phenotype by optical coherence tomography in 52 patients and measured the levels of circulating miRs across the transcoronary gradient. The overall plaque load was significantly correlated with transcoronary concentration gradients of miR-126-3p (P = 0.04), miR-145-5p (P = 0.01), miR-155-5p (P < 0.01), and miR-29b-3p (P = 0.02), but not with other miRs such as miR-92a-3p. In patients with a high extent of vulnerable plaques as assessed by the presence of thin-cap fibroatheromas (TCFAs), significantly higher transcoronary gradients were observed, particularly for miR-126-3p, miR-126-5p, and miR-145-5p (all P < 0.02). Transcoronary gradients of miR-126-3p (P < 0.01), miR-126-5p (P < 0.01), miR-145-5p (P = 0.01), miR-29b-3p (P = 0.03), and miR-155-5p (P = 0.02) demonstrated a significant discriminatory power to predict the presence of TCFAs (AUC > 0.7 for all). Moreover, aortic and venous coronary sinus levels of miR-29b-3p were inversely correlated with plaque fibrosis, a finding that is consistent with the anti-fibrotic activity of miR-29b-3p. CONCLUSION The overall plaque burden and plaque phenotypes are associated with changes in the kinetics of miR-concentrations across the transcoronary passage. Transcoronary gradients of the anti-atherosclerotic miR-126-3p and miR-145-5p correlated with the extent of TCFAs, suggesting that instable plaques may affect the local uptake or degradation of these miRs.

Identification of acute myocardial infarction in patients with atrial fibrillation and chest pain with a contemporary sensitive troponin I assay

BackgroundThe introduction of modern troponin assays has facilitated diagnosis of acute myocardial infarction due to improved sensitivity with corresponding loss of specificity. Atrial fibrillation (AF) is associated with elevated levels of troponin. The aim of the present study was to evaluate the diagnostic performance of troponin I in patients with suspected acute coronary syndrome and chronic AF.MethodsContemporary sensitive troponin I was assayed in a derivation cohort of 90 patients with suspected acute coronary syndrome and chronic AF to establish diagnostic cut-offs. These thresholds were validated in an independent cohort of 314 patients with suspected myocardial infarction and AF upon presentation. Additionally, changes in troponin I concentration within 3 hours were used.ResultsIn the derivation cohort, optimized thresholds with respect to a rule-out strategy with high sensitivity and a rule-in strategy with high specificity were established. In the validation cohort, application of the rule-out cut-off led to a negative predictive value of 97 %. The rule-in cut-off was associated with a positive predictive value of 88 % compared with 71 % if using the 99th percentile cut-off. In patients with troponin I levels above the specificity-optimized threshold, additional use of the 3-hour change in absolute/relative concentration resulted in a further improved positive predictive value of 96 %/100 %.ConclusionsTroponin I concentration and the 3-hour change in its concentration provide valid diagnostic information in patients with suspected myocardial infarction and chronic AF. With regard to AF-associated elevation of troponin levels, application of diagnostic cut-offs other than the 99th percentile might be beneficial.

Estimation of Values below the Limit of Detection of a Contemporary Sensitive Troponin I Assay Improves Diagnosis of Acute Myocardial Infarction

BACKGROUND The limit of detection (LoD) is the minimal amount of a substance that can be consistently detected. In the diagnosis of acute myocardial infarction (AMI) many patients present with troponin concentrations below the LoD of contemporary sensitive cardiac troponin I (cs-cTnI) assays. These censored values below the LoD influence the diagnostic performance of these assays compared to highly sensitive cTnI (hs-cTnI) assays. Therefore we assessed the impact of a new approach for interpolation of the left-censored data of a cs-cTnI assay in the evaluation of patients with suspected AMI. METHODS Our posthoc analysis used a real world cohort of 1818 patients with suspected MI. Data on cs-cTnI was available in 1786 patients. As a comparator the hs-cTnI version of the assay was used. To reconstruct quantities below the LoD of the cs-cTnI assay, a gamma regression approach incorporating the GRACE (Global Registry of Acute Coronary Events) score variables was used. RESULTS Censoring of cs-cTnI data below the LoD yielded weaker diagnostic information [area under the curve (AUC), 0.781; 95% CI, 0.731-0.831] regarding AMI compared to the hs-cTnI assay (AUC, 0.949; CI, 0.936-0.961). Use of our model to estimate cs-cTnI values below the LoD showed an AUC improvement to 0.921 (CI, 0.902-0.940). The cs-cTnI LoD concentration had a negative predictive value (NPV) of 0.950. An estimated concentration that was to be undercut by 25% of patients presenting with suspected AMI was associated with an improvement of the NPV to 0.979. CONCLUSIONS Estimation of values below the LoD of a cs-cTnI assay with this new approach improves the diagnostic performance in evaluation of patients with suspected AMI.

GDF-15 predicts cardiovascular events in acute chest pain patients.

Background Treatment of patients presenting with possible acute myocardial infarction (AMI) is based on timely diagnosis and proper risk stratification aided by biomarkers. We aimed at evaluating the predictive value of GDF-15 in patients presenting with symptoms suggestive of AMI. Methods Consecutive patients presenting with suspected AMI were enrolled in three study centers. Cardiovascular events were assessed during a follow-up period of 6 months with a combined endpoint of death or MI. Results From the 1818 enrolled patients (m/f = 1208/610), 413 (22.7%) had an acute MI and 63 patients reached the combined endpoint. Patients with MI and patients with adverse outcome had higher GDF-15 levels compared with non-MI patients (967.1pg/mL vs. 692.2 pg/L, p<0.001) and with event-free patients (1660 pg/mL vs. 756.6 pg/L, p<0.001). GDF-15 levels were lower in patients with SYNTAX score ≤ 22 (797.3 pg/mL vs. 947.2 pg/L, p = 0.036). Increased GDF-15 levels on admission were associated with a hazard ratio of 2.1 for death or MI (95%CI: 1.67–2.65, p<0.001) in a model adjusted for age and sex and of 1.57 (1.13–2.19, p = 0.008) adjusted for the GRACE score variables. GDF-15 showed a relevant reclassification with regards to the GRACE score with an overall net reclassification index (NRI) of 12.5% and an integrated discrimination improvement (IDI) of 14.56% (p = 0.006). Conclusion GDF-15 is an independent predictor of future cardiovascular events in patients presenting with suspected MI. GDF-15 levels correlate with the severity of CAD and can identify and risk-stratify patients who need coronary revascularization.

Adjusted Troponin I for Improved Evaluation of Patients with Chest Pain

The use of cardiac troponins (cTn) is the gold standard for diagnosing myocardial infarction. Independent of myocardial infarction (MI), however, sex, age and kidney function affect cTn levels. Here we developed a method to adjust cTnI levels for age, sex, and renal function, maintaining a unified cut-off value such as the 99th percentile. A total of 4587 individuals enrolled in a prospective longitudinal study were used to develop a model for adjustment of cTn. cTnI levels correlated with age and estimated glomerular filtration rate (eGFR) in males/females with rage = 0.436/0.518 and with reGFR = −0.142/−0.207. For adjustment, these variables served as covariates in a linear regression model with cTnI as dependent variable. This adjustment model was then applied to a real-world cohort of 1789 patients with suspected acute MI (AMI) (N = 407). Adjusting cTnI showed no relevant loss of diagnostic information, as evidenced by comparable areas under the receiver operator characteristic curves, to identify AMI in males and females for adjusted and unadjusted cTnI. In specific patients groups such as in elderly females, adjusting cTnI improved specificity for AMI compared with unadjusted cTnI. Specificity was also improved in patients with renal dysfunction by using the adjusted cTnI values. Thus, the adjustments improved the diagnostic ability of cTnI to identify AMI in elderly patients and in patients with renal dysfunction. Interpretation of cTnI values in complex emergency cases is facilitated by our method, which maintains a single diagnostic cut-off value in all patients.

Urinary neutrophil gelatinase-associated lipocalin and cystatin C compared to the estimated glomerular filtration rate to predict risk in patients with suspected acute myocardial infarction

INTRODUCTION Impaired renal function, reflected by estimated glomerular filtration rate (eGFR) or cystatin C, is a strong risk predictor in the presence of acute myocardial infarction (AMI). Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is an early marker of acute kidney injury. uNGAL might also be a good predictor of outcome in patients with cardiovascular disease. Aim of the present study was to evaluate the prognostic value of uNGAL compared to eGFR and cystatin C in patients with suspected AMI. METHODS 1818 patients were enrolled with suspected AMI. Follow-up information on the combined endpoint of death or non-fatal myocardial infarction was obtained 6months after enrolment and was available in 1804 patients. 63 events (3.5%) were registered. RESULTS While cystatin C and eGFR were strong risk predictors for the primary endpoint even adjusted for several variables, uNGAL was not independently associated with outcome: When applied continuously uNGAL was associated with outcome but did not remain a statistically significant predictor after several adjustments (i.e. eGFR). By adding cystatin C or uNGAL to GRACE risk score variables, only cystatin C could improve the predictive value while uNGAL showed no improvement. CONCLUSION We could show that cystatin C is an independent risk predictor in patients with suspected AMI and cystatin C can add improvement to the commonly used GRACE risk score. In contrast uNGAL is not independently associated with outcome and seems not to add further prognostic information to GRACE risk score.

Troponin I Assay for Identification of a Significant Coronary Stenosis in Patients with Suspected Acute Myocardial Infarction and Wide QRS Complex

Background Common ECG criteria such as ST-segment changes are of limited value in patients with suspected acute myocardial infarction (AMI) and bundle branch block or wide QRS complex. A large proportion of these patients do not suffer from an AMI, whereas those with ST-elevation myocardial infarction (STEMI) equivalent AMI benefit from an aggressive treatment. Aim of the present study was to evaluate the diagnostic information of cardiac troponin I (cTnI) in hemodynamically stable patients with wide QRS complex and suspected AMI. Methods In 417 out of 1818 patients presenting consecutively between 01/2007 and 12/2008 in a prospective multicenter observational study with suspected AMI a prolonged QRS duration was observed. Of these, n = 117 showed significant obstructive coronary artery disease (CAD) used as diagnostic outcome variable. cTnI was determined at admission. Results Patients with significant CAD had higher cTnI levels compared to individuals without (median 250ng/L vs. 11ng/L; p<0.01). To identify patients needing a coronary intervention, cTnI yielded an area under the receiver operator characteristics curve of 0.849. Optimized cut-offs with respect to a sensitivity driven rule-out and specificity driven rule-in strategy were established (40ng/L/96ng/L). Application of the specificity optimized cut-off value led to a positive predictive value of 71% compared to 59% if using the 99th percentile cut-off. The sensitivity optimized cut-off value was associated with a negative predictive value of 93% compared to 89% provided by application of the 99th percentile threshold. Conclusion cTnI determined in hemodynamically stable patients with suspected AMI and wide QRS complex using optimized diagnostic thresholds improves rule-in and rule-out with respect to presence of a significant obstructive CAD.